1. Field of the Invention
The present invention relates to a multilayer electronic device having excellent humidity resistance and a low volume change rate against temperature changes, wherein electrodes hardly break particularly in the outermost internal electrode layer in the stacking direction, and the production method.
2. Description of the Related Art
In recent years, along with downsizing and increasing capacitance of a capacity, there have been demands for a method of stacking thinner dielectric layers and internal electrode layers with less defects for multilayer ceramic capacitors.
To satisfy such demands, an increase of the number of dielectric layers and internal electrode layers and realization of thinner layers in a multilayer ceramic capacitor have been pursued. However, when a base metal Ni is used as the internal electrodes, a shrinkage difference arises between Ni and dielectric particles composing the dielectric layers because Ni has a lower melting point comparing with dielectrics and the difference of sintering temperatures is large. Consequently, it results in arising delamination and cracks, declining capacitance and rising a defective rate.
To overcome the disadvantages, there has been used a method of adding as co-material particles dielectric particles having the same composition as that of the dielectric layers to the electrode paste (refer to the Japanese Unexamined Patent Publication No. 2005-129591, the Japanese Unexamined Patent Publication No. 2004-311985, the Japanese Unexamined Patent Publication No. H07-201222 and the Japanese Unexamined Patent Publication No. H05-190373). As a result that the co-material particles are included with Ni particles in the electrode paste, spheroidizing due to grain growth of Ni can be suppressed to some extent. Particularly, the Japanese Unexamined Patent Publication No. 2005-129591 discloses a method of adding a co-material in an amount of 2 to 20 wt % for suppressing delamination and cracks between internal electrode layers and dielectric layers.
However, in a multilayer electronic device obtained by the Japanese Unexamined Patent Publication No. 2005-129591, electrode breaking could easily occur on an electrode surface of an outermost electrode layer in the stacking direction among the stacked electrode layers and crush or destruction could be caused due to intrusion of moisture from the broken part under a highly humid condition.
Therefore, a method of increasing an adding quantity of the co-material particles may be considered. However, when the adding quantity of co-material particles is increased, a change of capacitance against temperature changes becomes large and the temperature characteristics could be deteriorated.